1. Field of the Invention
The present invention relates to a stack of operational surface components for use with an oil or gas well. More particularly, the present invention relates to a transport and support frame for a blow-out preventer stack.
2. Background of the Related Art
A manifold having a series of valves and piping is typically used to contain the pressure of a reservoir, shut in a well, or control a production flow rate of a well. Commonly known manifolds include sub-sea wellheads, Christmas trees, and blow-out preventer (BOP) stacks. A BOP stack, in particular, comprises one or more BOPs to maintain oil, gas, mud, or other fluids within a well. BOPs are used to prevent unwanted or accidental exposure of pressurized fluids or gases during the drilling or workover of a well. In a well workover, for example, BOPs allow the well operator to insert and remove tubing or drill pipe within a wellbore while maintaining pressure in and around the tubulars.
BOPs are pressure containment and safety devices specifically designed to arrest the flow of a fluid or gas through a tubular or to seal an annular space between two coaxially arranged tubulars. There are numerous types of BOPs commercially available such as annular and blind types, for example. Annular type BOPs close off and seal annular spaces between coaxially arranged tubulars. Blind or xe2x80x9cshearxe2x80x9d type BOPs completely close off a well bore by crushing and/or shearing tubulars.
BOPs are typically vertically xe2x80x9cstackedxe2x80x9d to provide an effective and safe shut-off or isolation of any number of tubulars or annular areas within a wellbore. At least two BOPs are required to selectively seal an area around a tubular while permitting the passage of tools or connection joints into the well. Often times, a BOP stack consists of at least one blind ram, and at least one safety ram. The number of blind and safety rams are dependent on the working pressure of the wellbore. During a live well workover of the wellbore, a BOP stack will usually consist of at least two stripping rams in addition to the blind and safety rams. As a result, a BOP stack is often tall in relation to the other well surface equipment which makes the assembly, transportation, and servicing of the stack difficult for the well service company or operator.
A BOP stack may be pre-assembled and then transported to a wellsite. However, the assembled stack is rigid and brittle due to its height, making the stack susceptible to becoming loose or breaking at one or more interfaces between the individual BOPs. Most often, the BOP stack is jolted and bounced during transportation to a job site so that the connected flanges loose a fluid tight seal. Consequently, the BOP stack must then be re-tightened, re-inspected, and re-tested once installed at the job site.
Alternatively, the individual components of a BOP stack may be transported to and assembled at the wellsite. However, the assembly and disassembly of the individual components at the wellsite requires extensive man power and costly time because the size and shape of the stack severely restricts personnel access. Scaffolding is therefore separately assembled and disassembled to facilitate the assembly and disassembly of the stack.
Moreover, access to the individual components comprising the stack creates a problem once the stack assembly is completed or the pre-assembled stack is installed. A BOP stack requires frequent manipulation of its components throughout its use for which, service personnel need some type of scaffolding or other access to the stack. Proper access is required for safety considerations and also to prevent any damage to the stack itself which may result from climbing on the stack.
Therefore, there is a need for a method and apparatus for safely and easily transporting a pre-assembled BOP stack to a job site. There is a further need for a protective assembly around a completed BOP stack to facilitate the transportation of the stack to a wellsite. There is still a further need for an apparatus to protect an assembled BOP stack during transportation to a wellsite and to facilitate the use and maintenance of the BOP stack at the wellsite.
A method and apparatus is provided to permit safe assembly, transportation, and use of a stack of operational surface components. In one aspect, a transport and support frame is provided which is constructed and arranged to be disposed about the stack to prevent axial twisting, vibration, and bouncing of the individual components comprising the stack which may occur during the transportation, hoisting, or use of the stack. The transport and support frame holds the stack firmly, thereby reducing damage and eliminating valuable time and manpower to re-tighten and re-align the individual components of the stack.
In another aspect, the transport and support frame comprises a plurality of vertical members each having an upper end and a lower end, a plurality of upper horizontal members interconnecting the upper ends of the vertical members, a plurality of horizontal members interconnecting the lower ends of the vertical members, and a support structure to secure the stack within the frame. At least one bar is disposed through a plurality of apertures formed within at least one interior attachment member of the stack. The support structure comprises a plurality of horizontal members each having a first end and a second end wherein the first end is secured to the vertical members of the frame and the second end is secured to the bars. The support structure also comprises a plurality of diagonal members each having a first end and a second end wherein the first end is secured to the vertical members and the second end is secured to the bars or horizontal members.
A method of attaching a stack of operational surface components to a transport and support frame is also provided. The method comprises disposing an attachment member having a plurality of apertures formed in an outer surface thereof within the stack, inserting at least one bar within each apertures, and securing the bar to a support structure comprising: a plurality of vertical members each having an upper end and a lower end; a plurality of upper horizontal members interconnecting the upper ends of the vertical members; a plurality of lower horizontal members interconnecting the lower ends of the vertical members; a plurality of diagonal support members extending from the vertical members toward an interior of the frame; and a plurality of horizontal support members extending from the vertical members toward the interior of the frame.
In another aspect, an attachment member is provided that may be disposed on a riser, thereby providing a means for tensioning the riser from an offshore platform above.